Fourth Servo gone?

uArm Swift (Pro) Troubleshooting
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uArm Serial No.: UARM - 04021700B6
Firmware Version: 2.3.5
Operation System: Linux
uArm Controlling Method: Terminal on Serial

I cannot really determine if I am having some sort of hardware issue with the uarm swift.

Here is the arm, started up from default, rotated with G2202 N3 V45
and right after that sent the G2202 N3 V135 command. BTW, this is how
the suction cup rotates anyway, it’s not these particular two angles:

https://goo.gl/photos/kNuw4grZZX7iAEA46

OK, so, someone looking at this might say “Something wrong with the
servo”. But when you reset the arm, the suction cup returns to zero
pretty quickly. Here it is:

https://goo.gl/photos/feBfbYPzejqoHxiz6

In this video: I have started up the arm, rotated to G2202 N3 V45 and
once that finished, simply disconnect from the arm. Here, it is also
visible what I mention in another post, for some reason the arm jams
itself in that position.

Anyway, the point here is that just before the arm resets itself, the suction cup rotates to its zero position pretty quickly.

I am not sure if this is a problem with the servo or the feedback from the servo or a matter of a parameter.

I am more inclined to fix this myself instead of shipping the arm
back to uFactory. As long as I can get some help on what the key issue
might be. First thing I would do would be to check if there is any
constriction, anything that may have been over tightened. If that turns
out to be ok I am going to remove the servo and check it on its own. If
there are any problems with the servo itself, I could try replacing it.
Not sure if it is a special grade servo or if one can be shipped from
ufactory (?).

All the best
AA

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Can’t see the video links.

3

Thank you for letting me know, just edited the post.

4

AA looking at your video I would say you don’t have a servo issue. It resets fine and fast. I am having problems to even get my wrist to move? I am a novice to coding. But I notice the wrist servo doesn’t have an axis variable (i.e. x, y, z) which I think is a problem. However I am not sure. Anyway, can you post your code in blockly and I can try your code on my unit to see if I get the same response. I will try to get the code loaded tomorrow afternoon USA EST to test. I will post what I found right away.

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Hello

Thank you for your response.

The problem might not be with the servo itself but with the feedback from the servo or the firmware. I would appreciate a response on that part.

I do not understand what does “…the wrist servo doesn’t have an axis variable…” means (?). The wrist servo does not contribute to the position of the tip. It depends on which effector is mounted on the arm. If you have the pen holder, then yes, it does, but if you have the suction cup, the position is only determined by reach, rotation, height (in polar coords).

So, it does make sense to use a separate command to rotate it.

I cannot post the code to blockly because there is no code. All I do is connect to the arm and send commands to it manually. It should respond as expected in this way too.

All the best
AA

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Hi @aanastasiou

Please try to add a speed command at the end. e.g.: G2202 N3 V45 F0
F0 means full speed.

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Great! Thank you very much for your response, it worked indeed.

1 Like